25. There is every reason why we should largely avail ourselves of a science which above all others distinguishes the educated from the uneducated soldier, the man of intellect from the mere fighting machine. 26. We have shown not only that there is no valid objection to fortifications, but that they are the best means of defence for us, and that our metropolis is the point of all others that seems to stand in need of defence: it is the heart without a breast-plate. 27. We now therefore proceed to the practical application of the argument. _How_ should London be fortified? 28. In the minds of many may rise visions of an immense bulwark, a kind of great wall of China, drawn round London, and provided with ditches, drawbridges, and barred gates; and those who are acquainted with the customs of continental towns will probably connect them with barriers and _octrois_, and men examining your luggage and poking among your legs for contraband articles. On the contrary, now, thanks to our railways, our long-range guns, and to our volunteers, the fortifications which are necessary to secure London may be so unobtrusive, and so removed from the main highways, that no Londoner, save such as know what fortification really is, would ever realize the fact that they were in any way connected with its defence. 29. We only want half-a-dozen tolerably large forts, well placed, to form, as it were, the salient points of our defence. Let the reader refer to the diagram, and he will see six stars, one on Shooter’s Hill, one on Norwood Hill to the South of the Crystal Palace, one at or near Wimbledon, a fourth somewhere near Harrow, then at Mill Hill, and our last within good range of Enfield Lock. A set of dots (●) then come in about midway between the five spaces. [Illustration] 30. Let us now consider the significance of the stars which denote forts: and first, that on Shooter’s Hill, as the most important.